Photochemical reactions in commercial poly(oxy(2,6‐dimethyl)‐1,4‐phenylene)

The photooxidation of commercial poly(oxy(2,6‐dimethyl)‐1,4‐phenylene) (PPO) has been examined using absorption, luminescence (fluorescence and phosphorescence) and flash photolysis techniques. A comparison of the luminescence spectra of the polymer with that of the monomer 2,6‐dimethylphenol (DMP) shows that the chromophoric species responsible for light absorption in the near ultraviolet region 290–350 nm is the unit structure of the polymer itself. The fluorescence results also show the presence of an impurity chromophore in the polymer that absorbs in the visible region 400–550 nm. The flash photolysis experiments on both PPO and DMP give direct evidence for the formation of a phenoxyl radical indicating that main chain scission at the ether linkage is a major primary process in the photodeterioration of the polymer.